One of the most characteristic features of medieval literature is the richness and variety of the symbols it uses. Sometimes, these symbols are easy to recognize and interpret. Gawain's pentangle emblem is an obvious symbol, and the poet actually steps forward to explain its significance for the audience, bringing the narrative to a screeching halt in order to do so. Other symbols have meanings that will still be familiar even to modern readers. It is not particularly difficult to see how the fox may symbolize cunning and treachery, or how the deer may stand for fear or shyness. But in other cases, the meaning is not so easy to pin down: What about Gawain's armor, or the birds that decorate both knights' garments? Readers may not even feel certain that a particular item is symbolic at all.
Part of the difficulty in interpreting medieval literature comes from the fact that modern readers are unfamiliar with the cultural and intellectual background that a medieval audience would have brought to their understanding of a symbol. Some of this background has simply been lost to history, and scholars may have only scattered clues to help them understand a symbolic reference. Furthermore, a single symbol could easily have several contradictory meanings. A lion, for example, may represent Christ, St. Mark, or the devil, depending on the context in which it appears.
A more important part of the difficulty is caused by medieval ways of thinking about symbolism. Medieval thinkers believed that everything in the physical and natural world reflected the mind of God, the creator, and that by reading the significance of these symbols, human beings could come closer to understanding God. Thus, the entire world was filled with symbolic meaning. Moreover, medieval intellectual tradition did not limit a symbol to one meaning; instead, medieval thinkers derived multiple and sometimes quite diverse meanings for the symbols they found. An illustration of this intellectual habit can be found in the medieval method of interpreting the Bible, called exegesis. Medieval exegesis assumed at least four levels of meaning: literal, allegorical, tropological (or moral), and anagogical (or spiritual). At the literal level, a Biblical story is a simple presentation of facts. At the allegorical level, events and people become metaphorical representations: When Joshua blows his horn and the walls of Jericho collapse, for example, the story is an allegory of the Last Judgment, when the trumpet will sound and the world will come to an end. At the tropological level, a story teaches a lesson or gives a moral. At the anagogical level, a story conveys ultimate mystical or spiritual truths. Any Biblical text may have one or all of these levels of meaning operating at the same time.
Many modern critics have been determined to read all medieval literary works as straightforward allegories, in which everything is a symbol and every symbol has an easily identifiable meaning. Some medieval literature does fall neatly into this category. The Romance of the Rose is the most famous of medieval allegories, and even the Gawain-poet's Pearl is strongly allegorical. But Sir Gawain and the Green Knight stubbornly resists being reduced to such a simple formula. In fact, one of Sir Gawain and the Green Knight's most prominent features is its ambiguity. This ambiguity reflects one of its most important messages: Things are not always as they seem, and only human pride leads us to imagine that we can understand and control everything around us. The poet presents a beautiful but flawed world, in which good and bad are always mixed together, impossible to separate completely. In this world, "bliss and blunder, wrack and wonder" coexist, each taking their places in the turning cycles of life and of history. Sir Gawain and the Green Knight's symbolic richness — a sometimes frustrating richness — is a representation in miniature of this diverse and mixed world. Even if readers cannot ultimately pin down every one of its varied symbols, the hunt for them is no less rewarding.